Helicopter control



Jan. 16, 1951 M. D. BUIVID 2,538,082

HELICOPTER CONTROL Original Filed March 51, 1943 2 Sheets-Sheet 1 F xINVENTOR MICHEL D. BUlVlD ATTORNEY Jan. 16, 1951 Original Filed March31, 1943 Patented Jan. 16, 1951 V HELICOPTER CONTROL.

Michel, D. Buivid, Milford, Gonna, assignor to United AircraftCorporation, East. Hartford, Conn, a corporation of Delaware Originalapplication. March 31, 1943, Serial. No. 481,254, now Patent No.2,405,177, dated August 13,1946 Divided and this application February12, 1946, Serial No. 647,031

4,-Claims... I

This invention relates toimproved controls for helicopters, or the like,and is a division of my application Ser. No. 481,254, filed March 31,19:43, for Foldable Rotors, which issued as Patent. No. 2,405,777,August 13,1946.

More particularly, this invention provides. con.- trols for rotary wingaircraft in which the. operating connections between the body of thecraft and the rotor blades are arranged adjacent the blade connectionsin an improved manner to inhibit aberrations in control of the bladesdue to aerodynamic forces acting thereon causing movement of the bladesin flight, to thus render the controls precise under all conditions inflight.

In accordance with the above, an object of this invention is to provideimproved controls for helicopters, or the like.

Other objects and advantages lie in the details of construction andarrangement of parts and will be apparent from the followingspecification, and claims, and from the accompanying drawings whichillustrate What is now considered to be the preferred embodiment of theinvention.

Fig. 1 is a side elevation of a helicopter with the blades folded backand 0118;Of the bladespart- 1y folded back partially shown in. dot anddash lines.

Fig. 2 is a plan view of the helicopter with the blades folded.

Fig. 3. is a plan view on a larger scale showing the pitch changingmechanism ofone of the rotor blades.

Fig. 4 is a fragmentary plan view on an even larger scale of a portionof the pitch changing mechanism and the mechanism permitting the foldingof the blade.

Fig. 5 is a sectional view subs an ally along the line 5-5 of Fig. 4.

The rotary wing aircraft illustrated as a hellcopter has a power-drivensustaining rotor, generally indicated at l2, having several individualblades 14 (Fig. 2). Blades [4 are carried by the upper end of a shaft l8journaled in a head 20 in the fuselage It. This shaft, in the plane ofthe blade roots, has three symmetrically arranged fiat vertical surfacesfrom which three horizontal pivot pins 22 project each supporting a link24. The outer end of each link 24 has a vertical pin 26 pivotallysupporting a connector 28. A pin 30 extending from connector 28 fitsupon thrust and guide bearings 3! within a rotatable sleeve or bracket32 connected by pins 34 to a mounting bracket 36 on the inner end.- ofblade l4. Means, not shown for purposes of clearness of illustration,such as supportin wires (Cl. ITO-160,25.)

2: OITStOPS may be used to limit the extent: of movementor the bladeabout pin 22 and means such as shock absorbers may be used to limit the.extent of movement. of the blade. about the drag hing pin 26.

Brackets 32 and 361 are connected by a hinge joint comprisinginterengaging hinge lugs 33 and 48 which receive the. vertical pins 34.Thus, upon removal of either pin 34, the blade is free to hinge about.the axis of theother pin for movement either in the direction of bladerotation or in the opposite direction. With each blade similarlymounted, it is possible to fold th blades into the. position of Fig. 2from whatever position they come to rest.

The pitch of the blades. is progressively changed by movement. about.vthe pin 30 during, each rotation of the blades to control the attitudeof the" aircraft and the direction and rate of flight. To this end,bracket 32 has a projecting arm 42 connected by a removable pin 44. toan arm 46. Arm 46. has a hub 48 mounted to turn on. bracket 32 and is.connected by a link 50.110 an arm 52 (Fig. 5). Arm 52 is mounted on. theend of shaft 54, Fig. 3, which is journaled in bearing 56 on connector28. Shaft 54 is connected by universal joints 58 and 60 and spline 6| toa shortsshait. 62 turnable in. a bearing 64 on the upper end. of; rotorshaft. i8, and from Fig. 3 it will be noted. that universal joint 58'lies directly'over drag. hinge 26 Shaft 62' has a projecting arm 66connected by a. link 68 team arm 10 extending from acontrol plate 1 2',Fig. 1. This plate is part of the azimuth plate, the angularity ofwhich, with respect to shaft I8, controls the extent of the pitchadjustment of the individual blades and the point in each revolution atwhich the pitch change begins.

The upper plate 12 of the azimuth plate is supported on gimbals upon thedrive shaft and rotates with the rotor and the lower plate 16 isrestrained against rotation. Pitch adjusting.

rods 18 and are movable vertically by, and connect plate 16 with,adjusting nuts 82 and 84 which are controlled by movements of controlstick 86; cables being illustrated as one means of connecting the stickwith the nuts. As this mechanism is irreversible it will be apparentthat strains placed upon the pitch adjusting mechanism by a bladeallowed to droop to a position such as indicated by the dot and dashlines in Fig. 1 could be of great magnitude. A pitch changing mechanismstrong enough to support a blade without allowing it to droop would haveto be of excessive weight and strength.

Means, not shown, for purpose of clearness of illustration, forsimultaneously changing the pitch of all the blades, such as means forrsimultaneously vertically moving the shaft bear ings 64 for the severalblades, may be provided, and other types .of pitch adjustin mechanismmay, of course, be used, such for instance as the type shown anddescribed in United States Patents 2,402,349 and 2,415,148, issued June18, 1946, and February 4, 947, respectively. Even where reversible pitchchanging mechanism is used, the vertical movements of the blade tipsduring the folding operation may exceed the limits of travel of thepitch changing mechanism, and thus strain the pitch changing mechanism.

When any one of the blades is to be folded, one of the pins 34 isremoved and the blade is then swung about the axis of the other pin intothe position of Fig. 2 where the end of the blade is supported by abracket 19. As indicated above, durin the folding of the blade, failureto support the end of the blade may put an undesirable strain on thepitch controlling structure. To avoid this, pin 44 is withdrawndisconnecting the blade and the hinge joint from the pitch controlmechanism so that bracket 32 and blade M are free to turn with respectto arm 46. Thus, even if a blade is allowed to reach the slantingposition of blade M, Fig. 1, no strain is put on the pitch controlstructure since the bracket 32 turns within hub 48.

The same arrangement of parts permits fold ing of the blade when therotor comes to rest with any one of the blades set at a high pitch. Bydisengaging pin 44, the outer end of the blade is free to be movedvertically when the blade reaches the folding position, and no strain isplaced on the control structure by resting the end of the blade onbracket 14. This bracket may be removable to avoid interference with theblades in flight.

It is to be understood that the invention is not limited to the specificembodiment herein illustrated and described, but may be used in otherways without departure from its spirit as defined by the followingclaims.

I claim:

1. In combination with a rotor blade, a rotor axle, a hub mounted onsaid axle, a first pivotal connection adjacent the hub for guiding theblade in its coning angle changes, a second pivotal connection betweensaid first connection and said blade for guiding the blade in itsoscillations in the plane of rotation of said blade and a third pivotalconnection between the second pivotal connection and said blade aboutwhich said blade is movable to effect changes in pitch of the latter,means for changing the pitch of said blade comprising a shaft connectedwith said blade for changing the pitch thereof by rotation of saidshaft, said shaft having its axis lying substantially in the verticalplane containing the feathering axis of said blade, a bearing for oneend of said shaft mounted on said third connection, a bearing for theother end of said shaft carried by, said hub, and means also carried bysaid axle for rotating said shaft, said shaft including universal jointsand a sliding connection between said bearings whereby said blade maychange its coning angle and oscillate in the plane of rotation of saidblade without affecting the pitch setting of the latter,

2. In combination with a rotor hub supported on a rotor shaft andcarrying, upon a hinged blade support, a rotor blade free to change itsconing angle and to oscillate in the plane of blade rotation; means forchanging the pitch of said blade independently of the position thereofdue to coning angle changes and oscillations comprising, a rocker shaftadjacent said support and having an axis substantially lying in avertical plane containing the feathering axis of said blade, said shafthaving a bearing at one end in said blade support and at'its other endin said hub, control means for rocking said rocker shaft, and meansconnecting said rocker shaft, said control means and said blade, wherebymovement of said control means can feather said blade.

3. The structure set forth in claim 2, and in addition, a sliding jointin said rocker shaft.

4. The structure set forth in claim 2, and tiltable means in saidcontrol means to control the feathering cyclically.

MICHEL D. BUIV'ID.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 1,728,315 Viale Sept. 17, 19291,938,091 Wick Dec. 5, 1933 1,986,709 Breguet Jan. 1, 1935 1,994,488Sikorsky Mar. 19, 1935 2,415,148 Sikorsky Feb. 4, 1946

